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MK.
Asked: 2012-02-15 02:50:54 +0800 CST

Allowing only one user to log in at a time

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I have a special lab machine (linux) and two different users will be using this machine. They need to log in with the same userid. I want to prevent both of them from logging in at the same time. How can I do that?

I was thinking of starting with something simple like this - Use the users source IP-address and add some checks in .bashrc :

If a user logs in from IPAddress1 and there is already somebody ssh'ed in from IPAddress2 then print a big fat message.

linux

2 Answers

  1. Best Answer

    You can use pam_limits to do this too. Add a line like 

    fred    hard    maxlogins    1

    to /etc/security/limits.conf and it will only allow the user fred to log in up to 1 (maxlogins) times.

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  2. I think your plan sounds reasonable. Maybe do a check against something like last [username] | grep "still logged in" | wc -l in bashrc ? - could check for the ip there, also.

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